Attractive magnetic force has been used in the field of sealing movable doors. A magnetic weatherstrip assembly for thresholds is disclosed in U.S. Pat. No. 2,611,158 to Gregory. Gregory employs a magnetic weatherstrip assembly wherein a movable weatherstrip element is caused to be shifted into engagement with the door bottom under the influence of magnets installed in the door bottom.
Similarly, U.S. Pat. No. 3,604,152 to Protzman discloses a threshold assembly including complementary magnetic elements on the door and the threshold.
U.S. Pat. No. 4,192,101 to White discloses a door sealing apparatus having a metal strip applied to the door and a sealing strip having a magnetic portion applied to the frame such that the metal strip and the sealing strip magnetically engage upon closure of the door.
U S. Pat. No. 4,463,523 to Mailand et al. discloses a weatherstrip assembly for an entry door including a stiff portion adhered to the vertical surface of a door and a flexible strip portion extending below the bottom edge of the door and along a threshold. A first magnetic strip is attached to the flexible portion and a second metal strip is adapted to be adhered to the surface of the threshold so that the strips will be face to face and releasably seal between the door and the threshold when the door is closed. The assembly employs a pressure sensitive adhesive for adhering the assembly to the door and the threshold.
Other prior art door sweeps have used mechanical fasteners to retain a seal relative to movable doors. Specifically, the door sweeps are attached to the door by threaded fasteners. The door includes threaded apertures or recesses near the bottom of the door. The door sweep has corresponding holes through which the threaded fastener passes. The holes in the door sweep are usually oval or elongate to provide for adjustment of the sweep relative to the bottom of the door. However, the formation of holes in the door permanently degrades the appearance of the door. In addition, steel doors are susceptible to water penetration around upper seams and joints. The holes in the bottom of the door allow any water which penetrates into the door to weep out to the interior of the room.